This invention relates to a clean release laminate construction upon which a latent image may be formed, and in particular to a construction in which a releasable adhesive secures together two or more sheets upon which latent images may be formed through the use of chemical carbonless techniques.
Numerous types of businesses produce a wide variety of labels, nameplates, identification cards, tags, forms, and the like in larqe quantities. Each such product typically has specific indicia printed thereon by high speed printing devices. It is desirable to produce such products on a continuous web, with individual labels forms, or the like being adhesively attached to the web.
Additionally, manufacturers of quality products desire a procedure for permitting them to inspect samples of products and to determine quickly whether the sample is genuine or not. Many consumer goods are counterfeited and distributed with phony labels or tags. In many instances, it would be desirable to be able to have information on the label or tag of the product, such as clothing or other consumer goods, which will enable the manufacturer to identify the item and which contains information which will permit it to be tracked to its source.
Further, certain important documents are subject to counterfeiting. For example, checks, money orders, automobile titles and registration forms, birth certificates, or any other document which has value in itself or identifies another product of value may be a counterfeit. Accordingly, there is a need for a procedure for identifying such documents as genuine or not.
In the past, pressure sensitive adhesives have been utilized to secure the labels to a continuous web during printing. Typically. labels or the like were attached to a silicone release liner by a pressure sensitive adhesive. Customarily, when the pressure sensitive adhesive label was removed from the release liner, the label was attached to another surface by means of the tacky adhesive backing on the label. However, in some instances, it is desirable to be able to have both surfaces of a label or the like, and also the surface of the web from which the label is released, to be clean and non-tacky. Such products are manufactured by the Standard Register Co. and are known as clean release products and are typically used as sew on labels, nameplates, and identification cards.
Previously, such clean release products have been made through the use of so-called releasable or fugitive adhesives. These releasable adhesives exhibit cohesive (internal) failure instead of the usual adhesive/adherend failure exhibited by typical pressure sensitive adhesives. These releasable adhesives are compositions which form relatively weak bonds, but which adhere well to paper and other surfaces. Failure occurs within the releasable adhesive film itself when a layer of a laminate is subjected to peeling forces. This class of adhesives can be formulated to provide a range of cohesive strengths.
When cohesive failure occurs in such releasable adhesives, a thin film of adhesive remains on the back surface of the face sheet, on the face of the backing sheet or both. However, the film does not exhibit tack and has no adverse effect on the appearance or handling characteristics of the product. Moreover, the surface can be readily printed on.
In some instances, it is desirable to have a product which can be imprinted and which has the added function of providing one or more duplicate copies of the printed information. For example, Singer, U.S. Pat. No. 3,383,121, teaches a self-adhesive copy label which is affixed to a backer sheet by means of a pressure sensitive adhesive. Singer utilizes a multilayer structure which includes a self-contained carbonless sheet which produces the duplicate copy when the label is subjected to printing impact forces. However, in the Singer structure, care has to be taken to isolate the carbonless reactants from the pressure sensitive adhesive layer. Moreover, the labels of Singer have a tacky surface after delamination.
Likewise, Lockhart, U.S. Pat. No. 4,277,089, teaches the use of a removable label product which is adhered to a backer sheet through the use of pressure sensitive adhesive. The backer sheet itself comprises a self-contained carbonless product which provides a duplicate copy when the face sheet is subjected to impact printing forces. Like Singer, the peelable label of Lockhart has a tacky surface.
Further, in some instances, it is desirable to form an image or imprint information on a tag, label, or other document which is not visible to a consumer, but which can be made visible upon inspection to determine the genuineness of the article. Accordingly, the need still exists in the art for a clean release product which can provide a latent image of information printed onto a face sheet or label and which product can be readily removed from a laminate construction resulting in both a nontacky top sheet or label and a non-tacky web or backing sheet surface.